Nitro lacquer cure time

I'm helping a friend who is retiring and wants to build instruments pretty much full time in order to be able to be able to take a forced retirement. He's been building acoustic guitars for several years now but not making any money at it. I'm helping him with a plan to turn his hobby into a business.

The biggest issue I'm seeing is his very high cost of work-in-progress. He has several built in delays and I'm wondering if they are really needed.

The question I have is how long after the final buffing do you let an instrument cure before you mount the hardware and do the final setup? He waits at least a month for the finish to cure after final buffing. Is that about right?

[Bill Snyder]

Are you sure he does not wait the month before final buffing? I believe two - four weeks is common with the four weeks being better. The lacquer shrinks up as it cures and you don't want to do your final buffing of it just to have it shrink a noticeable amount afterward.

[monradon]

Nitro if three or more coats they recommend 30 days to harden before doing anything . I use reranch products for touch up and small jobs. Alot of the Mandos coming over are nitro lacquer.

[Michael Lewis]

You guys will get everything sorted out, eventually. Personally, I ruined a great hobby by taking it to the professional level. Now I have to do it even when I don't feel like it because I need the money and customers want their instruments. It was so much more enjoyable when it was just a hobby and I could just do what I wanted to. Don't get me wrong, I do enjoy my work, as I have learned over the years to appreciate the big picture and realize that my work is only a small part of my life, even if it does take up most of the time.
Have another cup?

[Hans]

Hobbies are always more fun than work!
The wait time for lacquer curing largely depends on the look you are after. For that glass smooth look, wait 3-4 weeks. For that look that old mandolins have with the grain showing, I used to sand and buff the next day.

He actually does allow the finish to cure for a month before he does the final buffing to high gloss. Then he waits another month before he mounts the hardware. He lets all his glue joints cure for at least two weeks after they are dry before he starts the finishing. Once he has the instrument all set up he keeps it for another month or so, playing it for a few minutes every day, just to make sure everything is OK.

In the past he has only done three or four guitars a year. He waits until he sells one and uses that money for the materials to start another one and to purchase more tools and equipment. Since he is being forced to retire and cannot really afford to he is going to have to do something to supplement his income. Part of the puzzle was figuring out how many instruments will have to make each year in order to get the required income. The next part of the puzzle is figuring out whether or not he can make that many instruments.

If this isn't going to work he will probably have to get a job bagging groceries...

[olddavy]

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[jk245]

Is it common for a major maker to mount the bridge before the laq cured hard?
My otherwise great looking Gibson A5L, built about 5 years ago, has an impression in the finish under the bridge which can be seen only when the bridge is removed.

That's the big question about cure time. A finish can look and feel fully cured but still seem to move or ooze or seep or something when some pressure point is applied for a period of time. That's the issue we have right now. How long do we let an instrument sit that is within a couple of hours work of being shipped? Not long enough is really bad but too long causes cash-flow issues that must be planned for.

Bigger companies can sometimes push a product out the door a bit early in order to make some goal upper management has set. An individual maker might have to do the same thing in order to make the mortgage or feed the family.

[Bill Snyder]

Some of the big companies such as Taylor use a UV cured polyester that cures almost immediately in their curing booths. Mario Proulx (a one man shop) uses a polyester finish that cures rapidly. He has shared information about its use over at the Musical Instrument Maker's Forum (mimf.com) in quite a bit of detail. He has posted a bit on the Cafe about it also.

[Michael Lewis]

An added thought, you have to "run the numbers" to find how many instruments it will take to keep the wolf from the door. Accurate accounting and bookkeeping are really important in this regard. Our tax dollars are at work in the Small Business Development Centers around the country, and are a good resource for such information. If your firend is going to make a living at making instruments he will have to understand how business is structured and run, and the SBDC can really help in this regard. They cannot help get your posterior off the sofa and out to the shop though. In that regard you have to be a self starter. There are a lot of hats to wear, luthier, bookkeeper, sales person, customer relations expert, shop gofer, advertising director, etc. When you are self employed you can have the boss from hell and a demanding prima donna employee all at the same time.

The business part of it is the reason I'm involved. That's what I do and people are silly enough to pay me for it. We know how many instruments have to be built and sold each year (12). We also know that he can indeed produce the required number of instruments, and actually several more if he wanted to work at it full time. Since he will have a pension and health benefits it isn't nearly the stretch it would be if he needed to earn full-time money.

His current procedures will require him to have at least eight instruments in progress at one time with a delivery rate of one per month. He only has space in his shop for six so he would have to make some more room. Obviously it would be a lot easier, and require less capital, if he could shorten the start to finish time to only require six instruments in progress at a time. The gating items for that to happen are the wait times.

Of course if he could sell the instruments for a lot more money it would reduce his production requirements but that isn't something he can be sure of at this point.

[Mario Proulx]

If he's building one per month, the wait time for the nitro is moot. Build that first one, spray it, hang it up and build the next one. By the time he sprays the next one and hangs it up, the first one is ready to level and buff. By the time the setup is done and it has shipped, and he builds the 3rd one, that 2nd one is ready to level and buff. And thus, the cycle will continue, with never a lost minute waiting for the finish to cure.

Mario, are you saying that it is OK to go ahead and mount the hardware and set it up immediately after buffing? That's what I really want to hear.

The problem is he has a lot hang time in his process. Basically build it, hang it up for two weeks for the glue to cure, spray it, hang it up for a month, buff it, hang it up for a month, set it up, let it settle for a month, ship it.

His build process is 3 months long and includes several points where he lets parts settle after being worked to be sure nothing bad is going to happen to them. He is receptive to the idea of building parts in batches which will allow them to settle before he needs them but he is for some reason quite sure the finish needs to cure for an additional month after buffing. It is that additional month that is making the scheduling a problem for me.

[sunburst]

First of all, "time is money".
I know we've all heard and read that so many times that it doesn't make much of an impression when we hear it again, but it is at the core of what I'm about to write here, so I said it again to apply it to this. If your friend wants to make money building guitars, he needs to conserve both in the process in order to make the amount of money he wants to.

It's true that your friend could increase the number of guitars in the "pipeline" in order to raise production and continue to let glues and finishes cure for excessive lengths of time, but in order to do so, he needs more space, as you've said. Space costs money, so it follows that using less space by allowing less time for curing saves money.
Specifically, waiting at least two weeks for glue joints to cure is simply not necessary. Nearly all glues cure in 24 hours or less. Glues and adhesives with water content do add some moisture to wood, and it can take longer than 24 hours for the moisture to leave the wood, but we're working with a range of acceptable moisture content in the wood anyway, and the moisture added generally doesn't raise the moisture content beyond that range. It is also true that the moisture added by such glues or adhesives is initially localized near the glue joint and that level sanding too early can lead to shrunken glue joints, but a couple of days is plenty to take care of that in wood as thin as that used in guitars, and the first 24 hours (the time it takes the glue to cure) is generally enough.
Furthermore, the extra moisture is not trapped by the finish, only slowed in it's journey out of the wood (assuming that the relative humidity is maintained so that the wood is losing moisture and not actually gaining moisture, and by the way, any extra space needed for all those instruments being stored needs to be "climate controlled", and that costs money).
So, excessive time waiting for glue joints to cure costs money and does no particular good much beyond 24 hours.

Lacquer does need some cure time before buffing for a smooth surface and good gloss. Three weeks is not excessive.
Lacquer does continue to harden for quite some time after that, but very slowly. I think it is excessive to wait more weeks after buffing for the same reason that it is excessive to wait weeks for glue to cure; storage space is expensive.
Installing hardware right after buffing is common, and not a problem. Maximum hardness of lacquer probably takes years (guessing here), so the hardware has to go on before the lacquer reaches maximum hardness anyway. Waiting weeks wastes money.


Playing the guitars daily for a month or so after they're done, well, now we're heading toward ridiculous. We're still using expensive storage space, but now we're using valuable luthier time too (time is $). OK, a few minutes playing each day doesn't sound like much, but if there are 8 guitars in the "pipeline" it adds up pretty fast.


As Michael and Hans mentioned earlier, turning a hobby into a business can be a problem for people. If your friend likes building guitars, and likes waiting excessive amounts of time for glues and finishes to cure, that's fine...for a hobby, but if he want's to build as a business and make money, he's got to quit wasting time and space with cure times well beyond the "point of diminishing return".

[jk245]

When you are self employed you can have the boss from hell and a demanding prima donna employee all at the same time.

You do not have to be an instrument maker for this to be true.

How many of the self-employed are so driven that we spend an extraordinary amount of time to accomplish our objective to be a success.

John, thanks so much for that post. Yours and the others will be used to encourage him to streamline his processes, and wait times, in order to be able to make this a go. It isn't anything I haven't tried to tell him but he will probably listen to those of you who actually do this.

He is in a rather enviable position needing only a fairly limited profit from this venture in order to cover the gap between pension and living expenses. He can either spend 20-30 hours a week building instruments or bagging groceries.

I hope I get mandolin number one from him before he gets too famous!

<I hope I get mandolin number one from him before he gets too famous!>

Well, he may choose to keep it around for sentimental value. But unless he is already *famous* for building other instruments or somehow becomes * famous * before completing his first mandolin ,
I'm sure you'll be able to beat the rush.

[sunburst]

He is in a rather enviable position needing only a fairly limited profit from this venture in order to cover the gap between pension and living expenses.

...and under the heading of: none-of-my-business,
If he can lower his living expenses, he can build more leisurely, perhaps enjoy it more, and the income could be gravy instead of necessity. (Building isn't all we luthiers learn! )

Part of the fun for me of this puzzle is his leisure time. He is a golfer and a flyfisherman. If it weren't for the golf and fishing he probably wouldn't need to earn any extra money at all.

He wants to avoid a part-time job where he is scheduled to appear at specific times. He does have the discipline to be able to build instruments on a schedule - as long as the schedule is in hours-per-day rather than specific times of the day.

After meeting with him today and talking to the dealer who has sold all his previous guitars it looks like he is going to get a part-time seasonal job and work his way up to building instruments as his sole extra-income source.

So six guitars (and hopefully one mandolin) the first year and he will make the decision whether to go further when he gets confindence that his guitars will continue to sell. Probably the most rational plan given the circumstances.